Injection molding nozzle having an annular flow tip

ABSTRACT

A nozzle in an injection molding machine allows for smooth, blended melt flow into a mold cavity. In one example, this is accomplished through use of a nozzle having a nozzle body with a nozzle melt channel in fluid communication with a manifold melt channel and a nozzle tip. The nozzle tip includes a first melt channel in fluid communication with the nozzle melt channel and a plurality of release melt channels between the first melt channel and an annular melt channel. The annular melt channel is formed between a retaining device and the nozzle tip. The annular melt channel includes a decompression chamber in fluid communication with respective ones of the release melt channels and a compression chamber between the decompression chamber and a mold. A pressure difference formed between the respective release melt channels and the decompression chamber and between the decompression chamber and the compression chamber blends the molten material to even and balance flow into the mold cavity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 60/575,841, filed Jun. 2, 2004, whichis incorporated by reference herein in its entirety.

This application is related to co-pending U.S. Ser. No. 10/______ filed______, which claims benefit under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 60/575,842, filed Jun. 2, 2004 (Atty.Docket Nos. 2107.1670000 and 2107.1670001), which are incorporated byreference herein in their entireties.

BACKGROUND

1. Field

The present invention is related to a nozzle for an injection moldingapparatus.

2. Related Art

In many injection molding systems available today, the systems includean injection molding machine having one or more nozzles for receivingmelt from a manifold and transferring/distributing the melt to one ormore mold cavities. This portion of an injection molding machine isoften referred to as a cold runner or a hot runner system.

For injection molded parts of various colors, a first color moltenmaterial must be flushed from the system so that a second color moltenmaterial may be run through the injection molding machine to produceparts of different color. Residue material from the first/subsequentcolor of the molten material conventionally causes numerous shots ofinjection molded products to be defective because they have anundesirable blend of two colors of molten material. It is common for asubstantial number of products to be defective in this way requiringmultiple injection cycles to clear the runner system before useableproducts are formed.

Additionally, or aside from when color change may be a problem,unidirectional molecular orientation and weld/flow lines can be apotential cause for weakness in the structural integrity, dimensionalaccuracy, or cause unwanted birefringence of a molded product.

Therefore, what is needed is a system and method that substantiallyreduces residue of molten material in a gate area of an injectionmolding machine. Additionally, or alternatively, what is needed is asystem and method for eliminating or substantially reducingunidirectional molecular orientation and/or weld/flow lines in a moldedproduct.

SUMMARY

One embodiment of the present invention provides a nozzle for aninjection molding apparatus. The nozzle includes a nozzle body, a nozzletip, a retaining device, and an annular melt channel. The nozzle bodyhas a nozzle melt channel, which can be in fluid communication with amelt channel in a manifold. The nozzle melt channel has a nozzle meltchannel longitudinal axis. The nozzle tip includes first and second meltchannels. The first melt channel is in fluid communication with thenozzle melt channel and has a first melt channel longitudinal axis thatis coaxial with the nozzle melt channel longitudinal axis. The secondmelt channel is in fluid communication with the first melt channel andhas a second melt channel longitudinal axis that, in one example, issubstantially normal with respect to the first melt channel longitudinalaxis. The retaining device can be used to position the nozzle tip withrespect to the nozzle body. The annular melt channel is formed betweenthe tip and the retaining device.

Another embodiment of the present invention provides a nozzle includinga nozzle body and a seal device having an annular melt channel. Thenozzle body has a nozzle melt channel, which can be in fluidcommunication with a melt channel in a manifold, and a nozzle meltchannel longitudinal axis. The seal device includes first and secondpieces. The first piece is used to position the second piece withrespect to the nozzle body. The annular melt channel is formed betweenthe first and second pieces, such that melt flows through the annularmelt channel before entering, for example, a mold cavity.

Another embodiment of the present invention includes one of the abovenozzles incorporated into an injection molding machine.

Further embodiments, features, and advantages of the present inventions,as well as the structure and operation of the various embodiments of thepresent invention, are described in detail below with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form a partof the specification, illustrate the present invention and, togetherwith the description, further serve to explain the principles of theinvention and to enable a person skilled in the pertinent art to makeand use the invention.

FIG. 1 illustrates a partial sectional view of an injection moldingmachine in which the present invention may be utilized.

FIG. 2 shows a side sectional view of a nozzle for use in the machine ofFIG. 1, according to one embodiment of the present invention.

FIG. 3 is an enlarged view of a portion B of the nozzle of FIG. 2.

FIG. 4 shows a cross-sectional view of the nozzle of FIG. 2 taken alongline A-A in FIG. 2, according to one embodiment of the presentinvention.

FIGS. 5, 6, and 7 show alternative nozzle configurations, according tovarious embodiments of the present invention.

FIGS. 8 and 9 are side sectional and cross-sectional views,respectively, of a nozzle for use in the machine of FIG. 1, according toone embodiment of the present invention.

FIGS. 10 and 11 are side sectional and cross-sectional views,respectively, of a nozzle for use in the machine of FIG. 1, according toone embodiment of the present invention.

FIGS. 12 and 13 are side sectional and cross-sectional views,respectively, of a nozzle for use in the machine of FIG. 1, according toone embodiment of the present invention.

FIGS. 14 and 15 are side sectional and cross-sectional views,respectively, of a nozzle for use in the machine of FIG. 1, according toone embodiment of the present invention.

FIG. 16 is a side sectional view of a portion of a nozzle for use in themachine of FIG. 1, according to one embodiment of the present invention.

FIGS. 17 and 18 show a side view and a cross-sectional view (taken alongline F-F), respectively, according to one embodiment of the presentinvention.

FIG. 19 shows a cross-sectional view of a portion of a nozzle, accordingto one embodiment of the present invention.

The present invention will now be described with reference to theaccompanying drawings. In the drawings, like reference numbers mayindicate identical or functionally similar elements. Additionally, theleft-most digit(s) of a reference number may identify the drawing inwhich the reference number first appears.

DETAILED DESCRIPTION

Overview

While specific configurations and arrangements are discussed, it shouldbe understood that this is done for illustrative purposes only. A personskilled in the pertinent art will recognize that other configurationsand arrangements can be used without departing from the spirit and scopeof the present invention. It will be apparent to a person skilled in thepertinent art that this invention can also be employed in a variety ofother applications.

One or more embodiments of the present invention provide a nozzle in aninjection molding machine that allows for an improved flow of a moltenmaterial into a mold cavity, which can substantially reduce or eliminateflow lines in an injected molded product. In one example, this isaccomplished through use of a nozzle having a nozzle body with a nozzlemelt channel, which can be in fluid communication with a manifold meltchannel, and a nozzle tip. The nozzle tip includes a first melt channelin fluid communication with the nozzle melt channel and one or morerelease melt channels between the first melt channel and an annular meltchannel.

In one embodiment of the present invention, the annular melt channel isformed between a retaining device and the nozzle tip. The annular meltchannel includes a decompression chamber in fluid communication withrespective ones of the release melt channels and a compression chamberbetween the decompression chamber and a mold cavity. In this embodiment,a pressure difference results between the respective release meltchannels and the decompression chamber and between the decompressionchamber and the compression chamber that acts to blend the moltenmaterial in the nozzle tip area more quickly and efficiently thancurrent systems, such that it enters a mold cavity without flow lines,i.e., weld lines.

In one example, the material used for the nozzle tip is a high thermallyconductive material, with a corrosion and abrasion resistance (e.g.,wear resistant). A plurality of holes or bores, i.e., release meltchannels, are located at a point where the nozzle tip separates from theretaining device. The holes are oriented with respect to a radial axis,and can be aligned with respect to a longitudinal axis or offset fromthis axis. The desired flow rate is used to determine the diameter ofthe exit holes.

In this example, and as discussed above, the nozzle tip is designed inconjunction with the retaining device to have the annular melt channelwith decompression and compression chambers. The nozzle tip holes orbores exit to the decompression chamber, which creates a circular flowof the molten material around the nozzle tip in order to mix/blend themolten material. Then, under the growing pressure of the molten materialin the decompression chamber, the molten material flows through thecompression chamber, which acts as a pressure regulator and sheargenerator. This leads to an annular flow in a hot area where the moltenmaterial further blends to eliminate flow lines and/or ease colorchange.

The compression of the molten material occurs up to a seal area, whichcan be at a downstream portion of the retaining device and the mold gatearea. As such, in the seal area a reduction of the annular surface ofthe nozzle tip, an increase in flow speed and shear rate of the melt,and an increase of the relative temperature of the molten material andhot runner components (e.g., the retaining device and the nozzle tip)allows for a re-melt of solidifying melt material in contact with themold, which improves color change, in such applications, as well as meltflow.

Overall System

FIG. 1 shows an injection molding system 100 in which the presentinvention may be utilized. System 100 includes a sprue bushing 102extending through a machine platen 104 for connection with a machinenozzle (not shown) that introduces a melt stream under pressure into theinjection molding system via sprue bushing 102. From sprue bushing 102,melt flows into a manifold melt channel 108 provided in a manifold 110.In this embodiment, manifold 110 is a hot runner manifold and it allowsthe melt stream to be distributed through manifold outlets 112 into meltchannels 114 provided in respective nozzles 116. Nozzles 116 arepositioned within nozzle bores 118 of a mold plate 120, such that aninsulative air space 119 is provided between nozzle 116 and mold plate120. Each nozzle 116 is in fluid communication with a mold cavity 122via a mold gate 124 so that the melt stream may be injected throughnozzle melt channel 114 and a nozzle tip 126 into the mold cavities 122.A heater 128 surrounds nozzle 116 in order to keep the melt flowing witha desired viscosity. Cooling channels 106 are provided in mold plate 120to provide cooling to mold cavities 122.

Exemplary Thermal Gated Nozzle

FIG. 2 illustrates a side sectional view of a nozzle, according to oneembodiment of the present invention, for use in the environment describein FIG. 1. In this embodiment, a nozzle tip 226 is configured as atorpedo type nozzle tip, as will be described in more detail below. Anozzle 216 includes a nozzle body 230, nozzle tip 226, and a retainingdevice 232. In one example, nozzle tip 226 and retaining device 232function as a two-piece nozzle tip/seal. Retaining device 232 positionsnozzle tip 226 within nozzle body 230. In this embodiment, retainingdevice 232 is threadingly engaged through threads 234 on an outer wall236 of retaining device 232 with complementary threads 238 on an innerwall 240 of nozzle body 230. When engaged, a shoulder 242 of retainingdevice 232 abuts a curved portion 244 of nozzle tip 226 to secure it tonozzle body 230. In one example, retaining device 232 also includes asealing portion 245.

In one example, retaining device 232 is made from a steel based, atitanium based, a ceramic based, or other thermally insulative material.

In one example, nozzle tip 226 is made from a copper based, a steelbased, or other thermally conductive material.

In another example, tip 226 is bimetallic and includes first and secondportions 246 and 248. In one configuration, first portion 246 is morethermally conductive than second portion 248, possibly making secondportion 248 thermally insulative. In an alternative configuration,second portion 248 is more thermally conductive than first portion 246,possibly making first portion 246 thermally insulative and/or wearresistant. In this example, a thermally conductive material is made fromsteel, copper, or the like based material. Also, in this example, athermally insulative material is made from a steel, titanium, ceramic,or the like based material. It is to be appreciated that other materialsthat function similarly to those described above would become apparentto one of ordinary skill in the art upon reading this description, andare contemplated within the scope of the present invention.

FIG. 3 is an enlarged view of portion B in FIG. 2, according to oneembodiment of the present invention. In this embodiment, nozzle tip 226includes a first melt channel 350 having a longitudinal axis 351 andthat is in fluid communication at an upstream end with a nozzle bodychannel 214. First melt channel 350 is in fluid communication at adownstream end with at least one second melt channel 354 having alongitudinal axis 353. In one example, longitudinal axes 351 and 353 offirst and second melt channels 350 and 354, respectively, aresubstantially normal with respect to each other. For example,longitudinal axes 351 and 353 are 90°±10° relative to each other. Secondmelt channel 354 is in fluid communication with an annular melt channel352 formed between nozzle tip 226 and retaining device 232. Annular meltchannel 352 includes a first portion 356 and a second portion 358.

Second melt channel 354 is a release or exit melt channel through whichthe molten material flows from first melt channel 350 of nozzle tip 226.Second melt channel 354 can be formed as a bore or a hole through a wallof nozzle tip 226. Depending on an application and/or material make-upof nozzle tip 226, there can be up to six release melt channels 354.Various other number of release melt channels 354 are also contemplated.

In one example, longitudinal axis 353 of release melt channel 354 issubstantially normal or perpendicular to longitudinal axis 351 of firstmelt channel 350. As discussed above, substantially normal can be about90°+/−10° for certain applications, and different ranges for otherapplications. In another example, longitudinal axis 353 of release meltchannel 354 is angled with respect to longitudinal axis 351 of firstmelt channel 350.

Release melt channel 354 of nozzle tip 226 is used to transmit themolten material to first portion 356 of annular melt channel 352, whichin this embodiment acts as a decompression chamber. A pressure of themolten material in decompression chamber 356 is reduced due to thematerial expansion allowed within the decompression chamber. Fromdecompression chamber 356, the molten material flows into second portion358 of annular melt channel 352, which in this embodiment acts as acompression chamber. Due to a restricted configuration of second portion358, pressure of the molten material is increased as the molten materialis forced through compression chamber 358 toward a mold gate 224 of moldcavity 222.

This arrangement of annular melt channel 352 balances the flow velocityand pressure of the melt exiting nozzle melt channel 214 resulting in aneven/balanced flow out of annular melt channel 352 and into mold cavity222.

In this embodiment, due to the “flushing” nature of the melt flowthrough the tip area of the nozzle there is not a conventional “bubblearea” between retaining device 232, tip 226, and mold gate 224. Forexample, a “bubble area” can be seen as a stagnant area betweenretaining device 232, tip 226, and mold gate 224 that fills withmaterial during a first shot. The material remains stagnant andtypically does not flush out between shots. In one example, the stagnantmaterial can be used to provide insulation between nozzle tip 226 and amold. Respective pressure changes in the melt between second meltchannel 354 and first and second portions 356 and 358 of annular meltchannel 352 causes the molten material to flow between nozzle meltchannel 214 and mold cavity 222 at a higher rate than in conventionalnozzles, thereby mixing and maintaining melt in a molten condition toreadily exit via mold gate 224.

In one example, this allows a better consistency of molten material dueto mixing before mold cavity 222, thereby reducing or eliminatingweld/flow lines within the molded product.

In another example, through use of this configuration, during colorchange, as discussed above, the previous color molten material isflushed out of nozzle 216 substantially within very few product cycles.This is substantially less than the 50-60 product cycles thatcustomarily are required before a previous color is fully flushed out ofa conventional nozzle arrangement.

FIG. 19 shows a cross-sectional view of a portion of a nozzle, accordingto one embodiment of the present invention. All elements shown in FIG.19 are similar to those shown in FIG. 3 and described above, except inthis embodiment seal 245 does not retain a nozzle tip 1926. Nozzle tip1926 is retained in nozzle 216 through use of threading engagementbetween threads 1970 formed on nozzle tip 1926 and threads 1972 formedon nozzle 216. In other examples, instead of threads brazing or othercoupling schemes could also be used.

FIG. 4 is a cross-sectional view of nozzle 216 taken along line A-A inFIG. 2, according to one embodiment of the present invention. In thisembodiment, three release melt channels 354 are used to carry melt fromnozzle tip 226 to annular melt channel 352 (which may have decompressionin portion 356). A specific number of release melt channels 354 isapplication specific, as are the parameters (sizes) of release meltchannels 354, decompression chamber 356, and compression chamber 358.

FIGS. 5, 6, and 7 shows various configurations of nozzle tips 526, 626,and 726 according to various embodiments of the present invention, wherecommon features are numbered in accordance with features previouslydescribed. A main difference between the nozzles shown in these figuresis a number of release melt channels 354.

In other embodiments, first and second portion 356 and 358 of annularmelt channel 352 do not include decompression and compression areas,respectively, and include other configurations.

FIGS. 17 and 18 show a side view and a cross-sectional view (taken alongline F-F in FIG. 17), respectively, of a nozzle tip 1726, according toone embodiment of the present invention. Nozzle tip 1726 has a pluralityof release melt channels 1754A on a first level and a second pluralityof release melt channels 1754B on a second level. In one example,release melt channels 1754A are offset with respect to release meltchannels 1754B. This can be done, for example, to provide anintercrossing melt flow. This allows for, for example, a substantialreduction weld/split lines as compared to only a single release meltchannel or a single level release melt channel environment. In variousexamples, a number of release melt channels 1754A on the first level canbe equal to or a different number that a number of release channels1754B on the second level.

FIG. 18 includes all elements described above for FIGS. 2 and 3, withthe alternative nozzle tip 1726, as described above for FIG. 17. In theexample shown in FIG. 18, release melt channels 1754A and 1754B exitfrom first melt channel 350 into first portion 356 of annular meltchannel 352.

FIGS. 8 and 9 are side sectional and cross-sectional views (looking intoline B-B), respectively, of a nozzle for use in the machine of FIG. 1,according to one embodiment of the present invention. A nozzle 816includes a nozzle melt channel 814 in a nozzle body 830. A nozzle tip826 is positioned with respect to nozzle body 830 using a retainingdevice 832. An annular melt channel 852 is formed between nozzle tip 826and retaining device 832. Nozzle tip 826 includes a first melt channel850 and a second, release melt channel 854. Annular melt channel 852includes a first portion 856 and a second portion 858. Most features ofFIGS. 8 and 9 are similar to similarly numbered features the embodimentsdiscussed above, unless otherwise noted. As best seen in FIG. 9, a maindifferent in this embodiment is a number of release melt channels 854,which in this example there are three.

FIGS. 10 and 11 are side sectional and cross-sectional views (lookinginto line C-C), respectively, of a nozzle for use in the machine of FIG.1, according to one embodiment of the present invention. A nozzle 1016includes a nozzle melt channel 1014 in a nozzle body 1030. A nozzle tip1026 is positioned with respect to nozzle body 1030 using a retainingdevice 1032. An annular melt channel 1052 is formed between nozzle tip1026 and retaining device 1032. Nozzle tip 1026 includes a first meltchannel 1050 and a second, release melt channel 1054. Annular meltchannel 1052 includes a first portion 1056 and a second portion 1058.Most features of FIGS. 10 and 11 are similar to similarly numberedfeatures the embodiments discussed above, unless otherwise noted. Asbest seen in FIG. 11, a main difference in this embodiment is the numberof release melt channels 1054, which in this example is six.

FIGS. 12 and 13 are side sectional and cross-sectional views (lookinginto line D-D), respectively, of a nozzle for use in the machine of FIG.1, according to one embodiment of the present invention. A nozzle 1216includes a nozzle melt channel 1214 in a nozzle body 1230. A nozzle tip1226 is positioned with respect to nozzle body 1230 using a retainingdevice 1232. An annular melt channel 1252 is formed between nozzle tip1226 and retaining device 1232. Nozzle tip 1226 includes a first meltchannel 1250 and a second, release melt channel 1254. Annular meltchannel 1252 includes a first portion 1256 and a second portion 1258.Most features of FIGS. 12 and 13 are similar to similarly numberedfeatures the embodiments discussed above, unless otherwise noted. Asbest seen in FIG. 13, a main different in this embodiment is a number ofrelease melt channels 1254, which in this example there are three.

FIGS. 14 and 15 are side sectional and cross-sectional views (lookinginto line E-E), respectively, of a nozzle for use in the machine of FIG.1, according to one embodiment of the present invention. A nozzle 1416includes a nozzle melt channel 1414 in a nozzle body 1430. A nozzle tip1426 is positioned with respect to nozzle body 1430 using a retainingdevice 1432. An annular melt channel 1452 is formed between nozzle tip1426 and retaining device 1432. Nozzle tip 1426 includes a first meltchannel 1450 and a second, release melt channel 1454. Annular meltchannel 1452 includes a first portion 1456 and a second portion 1458.Most features of FIGS. 14 and 15 are similar to similarly numberedfeatures the embodiments discussed above, unless otherwise noted. Asbest seen in FIG. 15, a main different in this embodiment is a number ofrelease melt channels 1454, which in this example there are three.

Exemplary Annular Melt Channel Dimensions

FIG. 16 is a side sectional view of a portion of a nozzle for use in themachine of FIG. 1, according to one embodiment of the present invention.In this embodiment, an annular melt channel 1656 is defined between anozzle liner 1640 and a retaining device 1642. Annular melt channel 1656includes a first inner diameter D1 formed in a first portion 1658 ofannular melt channel 1656 and a second inner diameter D2 formed in asecond portion 1660 of annular melt channel 1656. In this example, D1 issmaller than D2. This figure also shows an outer diameter D3 of annularmelt channel 1656.

CONCLUSION

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not limitation. It will be apparent to persons skilledin the relevant art that various changes in form and detail can be madetherein without departing from the spirit and scope of the invention.Thus, the breadth and scope of the present invention should not belimited by any of the above-described exemplary embodiments, but shouldbe defined only in accordance with the following claims and theirequivalents.

It is to be appreciated that the Detailed Description section, and notthe Summary and Abstract sections, is intended to be used to interpretthe claims. The Summary and Abstract sections may set forth one or more,but not all exemplary embodiments of the present invention ascontemplated by the inventor(s), and thus, are not intended to limit thepresent invention and the appended claims in any way.

1. A nozzle for an injection molding apparatus, comprising: a nozzlebody having a nozzle melt channel with a longitudinal axis; a nozzletip, including, a first melt channel in fluid communication with thenozzle melt channel, the first melt channel having a first melt channellongitudinal axis, and a second melt channel in fluid communication withthe first melt channel and having a second melt channel longitudinalaxis that is substantially normal with respect to the first melt channellongitudinal axis; a retaining device that positions the nozzle tip withrespect to the nozzle body; and an annular melt channel formed betweenthe nozzle tip and the retaining device.
 2. The nozzle of claim 1,wherein there are between three and six of the nozzle tip second meltchannels.
 3. The nozzle of claim 1, wherein the second melt channelcomprises one of a bore and a hole.
 4. The nozzle of claim 1, wherein afirst portion of the annular melt channel comprises a decompressionchamber.
 5. The nozzle of claim 4, wherein a second portion of theannular melt channel comprises a compression chamber.
 6. The nozzle ofclaim 5, wherein the second portion of the annular melt channelcomprises a compression chamber adjacent the first portion of theannular chamber.
 7. The nozzle of claim 1, wherein an area between thenozzle tip and a mold gate is devoid of a bubble area.
 8. The nozzle ofclaim 1, wherein the nozzle tip is made from a thermally conductivematerial.
 9. The nozzle of claim 8, wherein the thermally conductivematerial comprises one of a copper-based material or a steel-basedmaterial.
 10. The nozzle of claim 1, wherein the nozzle tip comprises afirst section made from a thermally conductive material and a secondsection made from a thermally insulative material.
 11. The nozzle ofclaim 10, wherein the thermally conductive material comprises one of acopper-based material and a steel-based material.
 12. The nozzle ofclaim 10, wherein the thermally insulative material comprises atitanium-based material.
 13. The nozzle of claim 1, wherein theretaining device comprises: a retaining portion that positions the tipwith respect to the nozzle body; and a sealing portion that insulatesthe tip from a mold plate.
 14. The nozzle of claim 13, wherein thesealing portion touches the mold plate.
 15. The nozzle of claim 1,wherein the retaining device is made from at least one of steel,titanium, and ceramic.
 16. The nozzle of claim 1, wherein the annularmelt channel comprises: a first portion having a first diameter andbeing in fluid communication with nozzle tip second melt channel, and asecond portion having a second diameter and being in fluid communicationwith the first portion of the annular melt channel and with a moldcavity, wherein the second diameter is smaller than the first diameter.17. The nozzle of claim 1, wherein the nozzle tip comprises a firstsection made from a thermally conductive material and a second sectionmade from a wear resistant material.
 18. A nozzle in an injectionmolding apparatus, comprising: a nozzle body having a nozzle meltchannel, the nozzle melt channel having a longitudinal axis; a nozzletip; a retaining and sealing device, such that a retaining portion ofthe device positions the nozzle tip with respect to the nozzle body anda sealing portion of the device insulates the nozzle tip from a moldcavity; and an annular melt channel formed between the nozzle tip andthe retaining and sealing device, such that melt flows through theannular melt channel before entering the mold cavity.
 19. The nozzle ofclaim 18, wherein the nozzle tip includes a channel having alongitudinal axis.
 20. The nozzle of claim 19, further comprising: anexit channel having a longitudinal axis that is normal with respect tothe longitudinal axis of the nozzle tip and that extends between thenozzle tip and the annular melt channel.
 21. The nozzle of claim 20,wherein the annular melt channel comprises: a decompression chamber influid communication with the exit channel; and a compression chamber influid communication with the decompression chamber.
 22. The nozzle ofclaim 18, wherein the annular melt channel includes a decompressionchamber.
 23. The nozzle of claim 18, wherein the annular melt channelincludes a compression chamber.
 24. The nozzle of claim 18, wherein thesealing device touches the mold cavity.
 25. An injection moldingapparatus, comprising: a manifold having at least one manifold meltchannel therethrough; at least one nozzle having a nozzle body includinga nozzle melt channel with a longitudinal axis; a nozzle tip, including,a first melt channel in fluid communication with the nozzle meltchannel, the first melt channel having a first melt channel longitudinalaxis, and a second melt channel in fluid communication with the firstmelt channel and having a second melt channel longitudinal axis that issubstantially normal with respect to the first melt channel longitudinalaxis; a retaining device that positions the nozzle tip with respect tothe nozzle body; and an annular melt channel formed between the nozzletip and the retaining device.
 26. The injection molding apparatus ofclaim 25, wherein there are between three and six of the nozzle tipsecond melt channels.
 27. The injection molding apparatus of claim 25,wherein the second melt channel comprises one of a bore and a hole. 28.The injection molding apparatus of claim 25, wherein a first portion ofthe annular melt channel comprises a decompression chamber.
 29. Theinjection molding apparatus of claim 28, wherein a second portion of theannular melt channel comprises a compression chamber.
 30. The injectionmolding apparatus of claim 29, wherein the second portion of the annularmelt channel comprises a compression chamber adjacent the first portionof the annular melt channel.
 31. The injection molding apparatus ofclaim 25, wherein an area between the nozzle tip and a mold cavity isdevoid of a bubble area.
 32. The injection molding apparatus of claim25, wherein the nozzle tip is made from a thermally conductive material.33. The injection molding apparatus of claim 32, wherein the thermallyconductive material comprises one of a copper-based material or asteel-based material.
 34. The injection molding apparatus of claim 25,wherein the nozzle tip comprises a first portion made from a thermallyconductive material and a second portion made from a thermallyinsulative material.
 35. The injection molding apparatus of claim 34,wherein the thermally conductive material comprises one of acopper-based material and a steel-based material.
 36. The injectionmolding apparatus of claim 34, wherein the thermally insulative materialcomprises a titanium-based material.
 37. The injection molding apparatusof claim 25, wherein the retaining device comprises: a retaining portionthat retains the tip with respect to the nozzle body; and a sealingportion that insulates the tip from a mold plate.
 38. The injectionmolding apparatus of claim 37, wherein the sealing portion touches themold plate.
 39. The injection molding apparatus of claim 25, wherein theretaining device comprises one of steel, titanium, and ceramic.
 40. Thenozzle of claim 25, wherein the annular melt channel comprises: a firstportion having a first diameter and being in fluid communication withnozzle tip second melt channel, and a second portion having a seconddiameter and being in fluid communication with the first portion of theannular melt channel and with a mold cavity, wherein the second diameteris smaller than the first diameter.
 41. The nozzle of claim 25, whereinthe nozzle tip comprises a first section made from a thermallyconductive material and a second section made from a wear resistantmaterial.
 42. A nozzle for an injection molding apparatus, comprising: anozzle body having a nozzle melt channel; a nozzle tip, including afirst melt channel partially in fluid communication with the nozzle meltchannel, the first melt channel having a first melt channel centralaxis, and a release melt channel in fluid communication with the firstmelt channel, the release melt channel having a release melt channelcentral axis; a retaining and sealing device that retains the nozzle tipwith respect to the nozzle body and provides a seal between the nozzleand a mold cavity plate; and an annular melt channel formed between thenozzle tip and the retaining and sealing device.
 43. The nozzle of claim42, wherein the annular melt channel comprises: a decompression chamberin fluid communication with the release melt channel, and a compressionchamber in fluid communication with the decompression chamber.
 44. Thenozzle of claim 42, wherein the release melt channel longitudinal axisis substantially normal with respect to the first melt channel centralaxis.
 45. The nozzle of claim 42, wherein the sealing device touches themold cavity plate.
 46. An injection molding apparatus, comprising: amanifold having a melt channel; a mold cavity plate having a mold gateand a nozzle bore therein; and a nozzle including, a nozzle bodypositioned in the nozzle bore, the nozzle body having a nozzle meltchannel in fluid communication with a melt channel in a manifold, thenozzle melt channel having a longitudinal axis, a nozzle tip in fluidcommunication with the mold gate; a retaining and sealing device, suchthat a retaining portion positions the nozzle tip with respect to thenozzle body and a sealing portion provides a seal between the mold gatearea and an insulative air space of the nozzle bore; and an annular meltchannel formed between the nozzle tip and the retaining and sealingdevice, such that melt flows through the annular chamber before enteringmold gate of the mold cavity.
 47. The nozzle of claim 1, wherein: thereare first and second ones of the second melt channels; the first one ofthe second melt channels is positioned along a first of the second meltchannel longitudinal axis; and the second one of the second meltchannels is positioned along a second of the second melt channellongitudinal axis, which is parallel to and spaced from the first one ofthe second melt channel longitudinal axis.
 48. The nozzle of claim 47,wherein each of the first and second ones of the second melt channelseach comprise a plurality of the second melt channels.
 49. A nozzle inan injection molding apparatus, comprising: a nozzle body having anozzle melt channel, the nozzle melt channel having a longitudinal axis;a nozzle tip; a sealing device that insulates the nozzle tip from a moldcavity; and an annular melt channel formed between the nozzle tip andthe sealing device, such that melt flows through the annular meltchannel before entering the mold cavity.
 50. A nozzle for an injectionmolding apparatus, comprising: a nozzle body having a nozzle meltchannel with a longitudinal axis; a nozzle tip, including, a first meltchannel in fluid communication with the nozzle melt channel, the firstmelt channel having a first melt channel longitudinal axis, and a secondmelt channel in fluid communication with the first melt channel andhaving a second melt channel longitudinal axis that is substantiallynormal with respect to the first melt channel longitudinal axis; asealing device that seals the nozzle tip with respect to a mold cavity;and an annular melt channel formed between the nozzle tip and thesealing device.